This is an application for renewal of a longstanding program to provide intensive training in modern methods of nephrologic research to clinically trained individuals with the M.D. or M.D./Ph.D. degree. Continued funding of seven stipends per year is requested for this joint training program that provides support for both adult and pediatric nephrology fellows. Although the highest priority of this program is to train physician-scientists, basic scientist trainees with the Ph.D. degree who are strongly committed to careers in kidney research are also supported whenever possible. Each year 3-4 new trainees are recruited into the program after completing residency training in internal medicine or pediatrics. Only fellows with a strong commitment to multi-year research training are recruited into the program. Training is provided in both laboratory-based and patient-oriented research. The training faculty is drawn from multiple clinical and basic science departments (Internal Medicine, Pediatrics, Biomedical Engineering, Cellular and Molecular Physiology, Cell Biology, Epidemiology and Public Health, Genetics, Immunobiology, Pathology, Pharmacology) and spans diverse biomedical disciplines relevant to kidney disease research (electrolyte physiology and pathophysiology, cell biology and experimental pathology, genetics and developmental biology, immunology and transplantation, vascular biology, tissue engineering, and clinical epidemiology and biostatistics). Although the core of research training is provided through work on a selected research topic under the supervision of an individual preceptor, training is enhanced by a broad array of teaching conferences, seminars and courses. Indeed, many recent fellows have enrolled in graduate degree programs specifically designed for training clinician investigators including the Investigative Medicine Ph.D. program, and the Program in Chronic Disease Epidemiology that leads to a Master of Science in Epidemiology and Public Health. Over the past 35 years this program has trained many leaders in academic nephrology, and the recent track record continues to be outstanding. The overwhelming majority of trainees who completed training during the past 10 years currently hold either full-time academic positions or research-related positions in industry, and many have successfully competed for career development faculty grants from the NIH or American Heart Association (e.g. K08, K23, Fellow-to-Faculty Transition Award) or have already obtained NIH R01 grants. The program also has made progress in achieving ethnic diversity, as four current fellows are underrepresented minority trainees.